Centrifugal compressor



G. FLUGEL.

CENTRIFUGAL COMPRESSOR.

APPLICATION FILED MAR. 15. I917.

1 26,043. Patented Dec. 23, 1919.

InVenLofl Gustav Fltlgel,

e MM His Jfttorney.

For a consideration of what I believe to fea s aria areous'rav E ITGEL, or BERLIN, GERMANY, 'ASSIGNOR T0 GENERAL ELECTRIC COMPANY,

' A CORPORATION or NEW YORK.

Y GENTRIFUGAL COMPRESSOR.

To all whom it may concern:

Be it known that I, GUSTAV FLfiCEL, a subject of the German Emperor, residing at Berlin, Germany, have invented certain new and useful Improvements 'in Centrifugal Compressors, of which the following is a specification.

ThepreSent invention relates to centrifugal compressors and has for its object to provide an improved structure in compressors whereby pulsation will to agreater extent than heretofore be prevented.

be novel and my invention, attention is directed to the accompanying specification and the claim appended thereto.

In the accompanying drawings, Figure 1 is a diagram as will be explained hereinafter; Fig, 2 is a diagrammatic section of .an impeller; Fig. 3 is a diagrammaticside elevation of a portion of the Impeller shown in'Fig. 2, Fig. 4 is. a diagram similar to Fig. 3 illustrating a modification, and Fig. 5 is a diagram of another modification.

It is already known that in centrifugal compressors the so-called pulsation area P, see Fig. 1, withinwhich the machine is not usable on account of the occurrence of pulsations always comes before the peak S of the characteristic curve, by characteristic being understood the well known graphic representation of the relation between the pressure H on the delivery side of the inachine or on the delivery side of an impeller and the suction'volume, the ordinates of the curve being plotted in terms of discharge pressure and the abscissae of the curve being plotted in terms of volume. With a pure falling characteristic, therefore, a centrifu gal compressor will not .pul sate at all. By apure falling characteristlc is meant a characteristic curve according, to which the pres-.

sure gradually drops as the volume increases. With 'multi-stage compressors the pulsation point P is moved beyond the peak S to the falling branch of the characteristic curve; but it has also been found that a compressor will not pulsate if each individual stage thereof is so equipped with wheels that, when tested individually, it has a purely falling characteristic, with constant density of the air sucked in. Thus, in order to reduce pulsations as much as possible, or to obviate them entirely, it is necessary to bring thepeak S of the characteristic curves of the dif- Specification of Letters Patent. Pamgnted Egg, 23', 1919, Application filed March 15, 1917. Serial No. 155,099.

obtain purely falling characteristics entirely.

I have discovered that this result may be reached if the angle of exit from the running wheel, or the diameter of the running wheel, is made variable. This result may be attained by a' construction like that shown in Figs. 2 and 3, in which 10 represents the center line of the shaft 11 of an impeller wheel; 12 the blades; 13 the admission opening to the wheel, and14 the wheel disks between which the blades 12 are located. While the ends of the blades of the running wheel are located in a circle having a diameter the wheel disks 14. extend to a diam-' eter D The result is that with a full amount of flow a pressure is established corresponding to a runnin wheel having the dlameter d with zero ow on the contrary the walls be forced to rotate and thus a comparatively greater pressure will be established equivalent to that which ordinarily would be obtained by a running wheel of the larger diameter D With increasing quantity of flow the influence of the friction of the walls will decrease according to the in creasing radial component of the velocity complete manner by a construction according to Fig. 4:. While the ends of the buckets have the same distance from the axis as the rims of the disk, the buckets instead of running forward constantly outside the circle of the diameter d .are bent sharply backward as indicated at 15, this being done by reason of the fact that with a full amount of flow they are no longer capable of accelerating the air which is flowing from the compressor. Consequently, in this construction also, in case of a full'supply, a delivery pressure will be established which corresponds to a running wheel of diameter 03 with zerofiow, a deliver pressure corresponding to a running w eel of the diameterD will be established; and with a par- .the entire massof air within the running wheel Wlll 1n consequence of the friction of mg to-wheel diameter intermediate between tial'supply, a delivery pressure correspondd and D will be established. By this means itis perfectly possible to produce purelyfalling characteristic curves.

- Itwill also be understood that the two arrangement's; viz; that shown in Figs. 2 and 3, and'that shown in Fig; 4, may be combined into a single structure, in which case the vanes would not only terminate short of the disks ofthe runningwheel, as shown in Figs. 2 and.3, but at their ends would becurved as shown in Fig. 4. Such an arrangement is shown in Fig. 5 in which 18 indlcates the vanes curved or bent sharply backward at theirradially outer ends as indicated at 19 and20 and the periphery of the disks of the running wheels. As will be clear from the figure the vanes 18 terminate short of the periphery of the disks 20. v

In accordancewi th the provisions ofthe patent statutes, I have described the principl f operation of my invention, together with the apparatus which Inow consider to represent the best embodiment thereof, but

I desire to have it understood that the apparatusshown is only illustrative, and that the invention can be carried out by other means.

What I claim as new and desire. to secure by Letters Patent of the United States, is,--

In a centrifugal 1eompressorior handling gases, which compressor is subject to pulsations at light load, an impeller Wheel having 'my hand this 28rd day of December, 1916.

oUsrAVFLI'iGEL.

Witnesses:

MAX HAMBURGER, Josnr Russian. 

